Ok, I had to slog through all 15 frickin' pages so I can say it honestly, but my biggest PP is when a post starts with:
"I didn't read the other responses but..."
Arrrggh!

In other words, I'm SO sure that MY response to you is the BEST I'm not even going to bother checking to see if anyone else has mentioned it first.
And because I'm too lazy to read the thread.
And because I'm a narcissist.
The best part is when the thread has veered sharply from its OP, and then when some imbecile does a IDRTORB, everyone else is like, you're an idiot.
I'm seriously thinking of putting anyone who starts a post with IDRTORB on ignore...